Melt butter in a saucepan, then add onion and celery and fry until well browned (but not burnt). Strain the vegetables from the butter and return butter to saucepan. Fry breadcrumbs in butter until golden and slightly dry. Combine with fried onion and celery, chives, dill, parsley, salt and pepper. Store for 1 week in the fridge, or for up to 3 months in the freezer.